Programming Elixir Chapter 16 Notes


Nodes-The Key to Distributing Services

Atoms can be registered globally across all nodes. This allows us to, for example, find the one generator in a set of nodes.

One globally registered atom is the group leader. All IO is done through the group leader. Exercise #4 demonstrates how the group leader can be managed.

  1. Inter-node security is determined by passing a cookie.

  2. By default, all nodes on a single machine are given access to each other.

  3. Cookies are transmitted in plaintext.

  4. Ticker.ex source code.

Nodes-1

Run a directory listing from two nodes.

Nodes-2

Why is the tick “about” every 2 seconds vs precisely every two seconds?

Answer

These are software timers, not hardware timers. Systems may have a lot of processes running which cause some small timer jitter.

Nodes-3

Alter the code so that successive ticks are sent to each registered client. I modified the exercise to include the parent on one of the ticks.

Answer

Source code source code.

Nodes-4

Reimplement as a ring of clients.

Answer

Ended up using the example from Paul Ewing

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